If you use folders for projects, then you are right that you cannot tag it, but you could go into the folders section and move that folder to the bottom of the list, which will cause it to appear further down and may help with prioritization.

If you use tasks with subtasks as projects, then you could update the tag or priority of the task. We have considered making tags and priority cascade down to the subtasks in some way, and we are also considering a bulk-edit tool to provide for an easy way to modify a bunch of subtasks at once.